horse color coat calculator

What this horse color coat calculator does

This horse color coat calculator estimates the likely coat color outcomes for a foal based on basic Mendelian inheritance. It combines parent genotypes at five major loci to generate a probability breakdown of expected visible colors. While no calculator can replace full DNA testing and breed-specific expertise, this tool gives a practical, genetics-based forecast that breeders and horse owners can use for planning.

The model is designed for clarity and educational use. You choose each parent's genotype, then the calculator builds all possible genetic combinations in offspring and converts those combinations into predicted phenotypes.

Genetic loci included in this calculator

1) Extension (E/e)

Extension controls whether black pigment can be produced. Horses with e/e are red-based (chestnut family), while horses with at least one E allele can produce black pigment.

2) Agouti (A/a)

Agouti controls black pigment distribution when black pigment is present. On an E_ background, A_ usually restricts black to points (bay), while a/a allows a more uniformly black coat.

3) Cream (N/Cr)

Cream dilution is dosage-dependent:

• N/N: no cream dilution
• N/Cr: single cream dilution (e.g., palomino, buckskin, smoky black)
• Cr/Cr: double cream dilution (e.g., cremello, perlino, smoky cream)

4) Gray (G/g)

Gray is dominant and progressive. Horses with G_ usually lighten with age, regardless of underlying base color. That is why results may display as “Gray (bay base)” or similar.

5) Dun (D/d)

Dun is a dominant dilution that lightens the body while often preserving primitive markings. In this calculator, dun modifies the base or cream-modified base into forms such as red dun, bay dun, grullo, dunskin, and related outcomes.

How to use the calculator effectively

• Enter known genotypes from DNA reports whenever possible.
• If unknown, use best estimates based on pedigree and observable color history.
• Run multiple scenarios to compare outcomes under different genotype assumptions.
• Treat percentages as probabilities, not guaranteed foal results.

Interpreting the results table

The output shows phenotype probabilities ranked from highest to lowest. A “most likely outcome” appears at the top for quick interpretation. If gray appears in the result set, remember the foal may be born a base color and then progressively gray out over time.

Because the calculator combines multiple loci independently, the number of possible outcomes can be large. This is expected and reflects realistic genetic variation in horse coat inheritance.

Limitations and best-practice notes

This calculator focuses on five major loci and does not include every known modifier or pattern gene (such as silver, champagne, pearl, mushroom, roan, tobiano, frame overo, sabino variants, and many others). Real-world phenotype can also be affected by incomplete penetrance, expression variability, recording differences, and visual misclassification.

For high-stakes breeding decisions, combine this calculator with:

• Comprehensive DNA testing
• Veterinary guidance
• Breed registry color rules
• Documented family color records

Quick FAQ

Is this a guarantee of foal color?

No. It is a probability model based on selected loci.

Why do I see gray listed with a base color in parentheses?

Gray masks the base coat progressively with age, but the base genotype still exists genetically and can be passed on.

Why do small genotype changes shift outcomes so much?

Single dominant or recessive alleles can dramatically alter the probability tree, especially when multiple loci are combined.